Array.map! + delete_if possible?

Ruby
1

I have an array of strings that I need to modify. I either need to
replace the string or delete the entry altogether. The only way I have
been able to do this is :

arr.delete("")

(0…arr.size).each do |i|
if arr[i].to_i == 1201
arr[i]=arr[i].to_s[8…-1].gsub(/"[^"]"/,’::’).gsub(/"./,"::")
else
arr[i-1] = arr[i-1] + arr[i].to_s[4…-1].to_s.gsub(/\s*/,"")
arr[i]=nil
end
end

arr.delete(nil)

Is there a better way ?

Also inside the else I get char 4->-1 of a string, but then need to
explicitly change it into a string for gsub to work. Otherwise it gives
me an undefined method ‘gsub’ for nilNilClass error.

2

Kassym D. wrote in post #1022385:

(0…arr.size).each do |i|

arr = [1, 2, 3]
(0…arr.size).each do |index|
p arr[index]
end

–output:–
1
2
3
nil

if arr[i].to_i == 1201
arr[i]=arr[i].to_s[8…-1].gsub(/"[^"]"/,’::’).gsub(/"./,"::")
else
arr[i-1] = arr[i-1] + arr[i].to_s[4…-1].to_s.gsub(/\s*/,"")
arr[i]=nil
end
end

What if the first string in the array doesn’t equal 1201? Is it your
intention to change the last string in the array? What if there is only
one string in the array?

3

On Fri, Sep 16, 2011 at 5:03 PM, Kassym D. [email protected]
wrote:

else

Also inside the else I get char 4->-1 of a string, but then need to
explicitly change it into a string for gsub to work. Otherwise it gives
me an undefined method ‘gsub’ for nilNilClass error.

–
Posted via http://www.ruby-forum.com/.

I honestly have no idea what this is supposed to do.

4

Is there a better way ?

Probably :slight_smile:

But, I also have a hard time trying to understand what you want to do.
Can you post some sample array(s) and some sample output that you want
to see?

Harry

5

On 17.09.2011 00:03, Kassym D. wrote:

I have an array of strings that I need to modify. I either need to
replace the string or delete the entry altogether.

irb(main):010:0> a = 10.times.to_a
=> [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
irb(main):011:0> a.map! {|i| i.odd? ? i : nil}.compact!
=> [1, 3, 5, 7, 9]
irb(main):012:0> a
=> [1, 3, 5, 7, 9]

The only way I have
been able to do this is :

arr.delete("")

(0…arr.size).each do |i|

arr.each_index do |i|

if arr[i].to_i == 1201
arr[i]=arr[i].to_s[8…-1].gsub(/"[^"]"/,’::’).gsub(/"./,"::")

Maybe:

arr[i] = arr[i].to_s[8…-1].gsub(/"[^"]*(?:"|\z)/,’::’)

Is this really what you want? First you convert all quoted sequences to
“::” and then you remove everything after the single remaining quote to
the end by “::”?

else
arr[i-1] = arr[i-1] + arr[i].to_s[4…-1].to_s.gsub(/\s*/,"")

arr[i-1] << arr[i].to_s[4…-1].to_s.gsub(/\s*/,"")

 arr[i]=nil

end
end

arr.delete(nil)

arr.compact!

Is there a better way ?

First we should clarify what you are doing. As far as I can see you
want to iterate the array and either modify element i or convert element
i and append it to element i - 1. From this it is clear that you cannot
use #map or #map! because those methods are intended to modify the
current object.

Also inside the else I get char 4->-1 of a string, but then need to
explicitly change it into a string for gsub to work. Otherwise it gives
me an undefined method ‘gsub’ for nilNilClass error.

So your statement that you have a String is not correct. You are
probably experiencing this effect

irb(main):017:0> s=“123”
=> “123”
irb(main):018:0> s[4…-1]
=> nil

A bit of sample data would be helpful…

Kind regards

robert

6

On Sun, Sep 18, 2011 at 2:05 PM, Adam P. [email protected]
wrote:

a = (1…10).to_a # don’t really need the to_a for this, but hey
=> [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]

a.select! { |e| e.odd? }
=> [1, 3, 5, 7, 9]

a
=> [1, 3, 5, 7, 9]

My bad. I left the conversion out of my example. With conversion you
cannot use #select. This is a better example:

irb(main):004:0> a = 10.times.to_a
=> [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
irb(main):005:0> a.map! {|i| i.odd? ? ('’ * i) : nil}.compact!
=> ["", “", "", "", "”]

But anyway, this scenario is also not what the OP apparently wants.

Kind regards

robert

7

On Sun, Sep 18, 2011 at 12:30 PM, Robert K.
[email protected] wrote:

irb(main):010:0> a = 10.times.to_a
=> [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
irb(main):011:0> a.map! {|i| i.odd? ? i : nil}.compact!
=> [1, 3, 5, 7, 9]
irb(main):012:0> a
=> [1, 3, 5, 7, 9]

A bit simpler:

a = (1…10).to_a # don’t really need the to_a for this, but hey
=> [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]

a.select! { |e| e.odd? }
=> [1, 3, 5, 7, 9]

a
=> [1, 3, 5, 7, 9]

8

Thanks for the answer. Here is the initial array.

arr[0]=1201 0 “userid” 1202 0 “lname” 1203 0 “mname” 1204 0 “lname” 1217
0 “password”
arr[1]=
arr[2]=4 0 emailaddress
arr[3]=1201 0 “userid” 1202 0 “lname” 1203 0 “mname” 1204 0 “lname” 1217
0 “password”
arr[4]=
arr[5]=1201 0 “userid” 1202 0 “lname” 1203 0 “mname” 1204 0 “lname” 1217
0 “password”

The email address line is random depending if the user inputed one or
not and may or may not show up.

I want to end up with this :

arr[0]=userid::lname::mname::lname::password::emailaddress
etc

In the end I iterate over this array and input the info data into a
database. I don’t think I can combine both loops because I need to check
index for the email and if found go back to index-1 for the rest of the
info and then input into database.

Also instead of using arr.delete("") could I not use
arr.delete(/[^14}*/), but does not seem to work.

@7stud : Good catch about the first entry not having 1201, I missed
that, but there is no chance of that happening.

9

On Mon, Sep 19, 2011 at 5:24 PM, Kassym D. [email protected]
wrote:

0 “password”

The email address line is random depending if the user inputed one or
not and may or may not show up.

I want to end up with this :

arr[0]=userid::lname::mname::lname::password::emailaddress
etc

In the end I iterate over this array and input the info data into a
database. I don’t think I can combine both loops because I need to check
index for the email and if found go back to index-1 for the rest of the
info and then input into database.

I picked the approach to identify fields by their number and create
records based on that.

Also instead of using arr.delete(“”) could I not use
arr.delete(/[^14}*/), but does not seem to work.

Kind regards

robert